EPITAXIAL-GROWTH OF IRIDIUM AND PLATINUM FILMS ON SAPPHIRE BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

Ir and Pt epitaxial films were grown on (0001), (1120BAR), and (0112BAR) sapphire by metalorganic chemical vapor deposition using Ir- or Pt-acetylacetonate precursors. The epitaxial growth was achieved at deposition temperatures between 500 and 600-degrees-C with the addition of oxygen to the source vapor. The film orientation and epitaxial relationships between films and substrates were determined by x-ray diffraction, x-ray pole figures, and reflection high energy electron diffraction. Ir films on (1120BAR) sapphire grow in [100] orientation. Ir or Pt films on (0112BAR) and (0001) sapphire grow in [111] orientation. Ir films on (0001) sapphire contain two in-plane orientations related by a 180-degrees rotation, while Pt films containing only one in-plane orientation can be obtained on (0112BAR) and (0001) sapphire.